Electra MPC Module Schematics

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
Post Reply
jsrfo
Posts: 25
Joined: 23 Feb 2010, 03:36
Been thanked: 1 time

Post by jsrfo »

Does anyone have schematics or traces of the old Electra Guitar MPC modules? Just picked up a nice MPC guitar, and would like to attempt to make a module board, but would like to first see the thought process behind them, as the guitar uses one 150K pot to control one parameter on the effect. Pretty simple, I'd assume.

Any help would be appreciated. I'd even buy a broken or functional module to work from.

User avatar
Nocentelli
Tube Twister
Posts: 2150
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 752 times
Been thanked: 673 times

Post by Nocentelli »

Some superb (and possiblly trace-able) gutshots here:

http://www.rivercityamps.com/electra/modules.php
brownwhopping wrote:How can I learn by reading threads an making circuits, when some day I can see a lawsuit or somebody beat me in the face for that?

Axldeziak
Posts: 26
Joined: 23 Feb 2019, 17:18
Has thanked: 5 times
Been thanked: 13 times

Post by Axldeziak »

Looking through their forum it seems the phaser circuit was an original E-H Small Stone using CA3094 OTA.

jrod
Resistor Ronker
Posts: 416
Joined: 09 Jan 2009, 15:24
Has thanked: 302 times
Been thanked: 40 times

Post by jrod »

Nocentelli wrote:Some superb (and possiblly trace-able) gutshots here:

http://www.rivercityamps.com/electra/modules.php
The Overdrive looks to be basically the "Electra Distortion" schematic that's been floating around for years, but without the clipping diodes.

For the Dynamic Fuzz though the PCB trace side doesn't match up with the components.

User avatar
Dr Tony Balls
Diode Debunker
Posts: 818
Joined: 07 May 2009, 15:29
my favorite amplifier: Sunn Model T
Location: Brooklyn, NY
Has thanked: 2 times
Been thanked: 102 times

Post by Dr Tony Balls »

Dont have any schematics, per se, but I can chime in with some info. Awhile back a friend sent me two MPC modules in hopes that could get them working. The problem being that I dont have an MPC guitar to test them on. So I built a little pedal that could accept MPC cartridges for testing and use. Bought a 10 pin edge connector and just hooked it up outside a stompbox like so:

Image

One cart was a distortion unit that I got working. The other was a phase shifter that I couldnt get to the bottom of so instead I set out to build a replacement circuit. You could print a PCB for this if you want, but I found that 0.15" pitch vero board was a close enough match for the edge connector. You just have to cut it to size and cut/file shoulders by the connector. Wound up putting a Magnavibe circuit on one:

[url=https://flic.kr/p/Xg3mcR]Image

jsrfo
Posts: 25
Joined: 23 Feb 2010, 03:36
Been thanked: 1 time

Post by jsrfo »

I have just designed replacement PCB's for the Power Overdrive and the Dynamic Fuzz, and they work. So, now I need to figure out module boxes for these. Made one of each, and they work just fine. I intend to do a different overdrive as well, as I started out with those two original, simple circuits.

If anyone has suggestions on the module boxes, it would be appreciated.I thought about 3D printing.

jsrfo
Posts: 25
Joined: 23 Feb 2010, 03:36
Been thanked: 1 time

Post by jsrfo »

So, I am in the process of obtaining 3D printed cases for module boards. Wish I knew how to embed a picture, but they're basically the same size as the originals, only dark grey.

I have my own overdrive, sold as a pedal called the El Mo, built into a card, and it works pretty nicely. Three trim pots to adjust the module level output, bass and treble. The guitar pot controls the gain, which also adds some level. I've found that setting the tones up allow for brightening up the neck pickup on my X330. I set the tone the way I like it on the bridge pickup with the tone pot at "5", and then I can roll of some highs on the bridge if I want, or add some highs on the neck pickup. Also, the ability to adjust the output level of the card provides the ability to set unity volume with the module turned on at any desired point on the module control pot, unlike the originals, which some actually had to be turned up fairly far for unity.

Anyway, I can currently build cards for the Electra Power Overdrive, my custom OD, and an Electra Distortion circuit with two germanium diodes at this point.

Looking if anyone has a true gut shot or schematic for the Dynamic Fuzz Module, or any of the other modules, I'd like to see if I could make boards for them as well.

Post Reply